Most modern vehicles include an air conditioning system which comprises a number of components including a compressor, condenser, receiver dryer, expansion valve and evaporator. The air conditioning system also includes a refrigerant or coolant that flows through each of the components in turn, and undergoes repeated phase changes from a liquid to a gas and back to a liquid.
When the air conditioning system in a vehicle is switched on, liquid refrigerant under pressure flows from the receiver dryer to the expansion valve. Here, the refrigerant expands to form a gas, and as it does so, the temperature of the refrigerant drops. The cool gas then enters the evaporator where it absorbs heat from the air that is flowing into the passenger compartment of the vehicle, causing the refrigerant to boil.
The low-pressure refrigerant vapor then enters the compressor. The compressor is typically driven by a drive belt connected to the engine's crankshaft. The compressor compresses the refrigerant vapor and pumps it as a high pressure gas to the condenser. The condenser is typically mounted in front of a vehicle's radiator and comprises a large number of cooling fins surrounding parallel tubes. As the refrigerant flows through the tubes, air flowing past the fins of the condenser removes heat from the refrigerant, and the refrigerant changes from a gas to a liquid.
The liquid refrigerant then enters the receiver dryer (also called a modulator). The primary function of the receiver dryer is to separate any remaining gas from the liquid refrigerant. The receiver dryer is also used to remove moisture from the refrigerant, and therefore, will typically include a chemical desiccant to remove water from the refrigerant so that it does not freeze in the expansion section of the system. The receiver dryer may further include a filter to remove any dirt from the liquid.
In some vehicle air conditioning systems, a sub-cooled section is located between the receiver dryer and the expansion valve. This sub-cooled section provides additional cooling for the condensed refrigerant to improve system efficiency.
Due to the multiple functions of the receiver dryer, this component is typically complex, and often incorporates a removable insert to allow the desiccant and/or the filter element to be replaced at intervals. The receiver dryer may also include multiple conduits to direct the flow of refrigerant.
It is an object of the present invention to provide a less complex receiver dryer.